Application of Passive Solar System

8/14/2019 Application of Passive Solar System

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Application of Passive SolarSystem in Building

Dr.(Er.) Bharat R. Pahari [B.E.(Civil), M.Sc.engg (Energy Efficiency), Ph.D.(Eng.Edu.)]

Associate ProfessorDepartment of Civil Engineering,

Institute of Engineering/TU, Pulchowk.


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Dr.Pahari/ 65-9-3 2

Basic Concept

Passive design is the process of efficient use ofenergy.

This can be achieved by the economic use ofresources in harmony with environment.

A substantial part of world energy consumption isfrom the buildings.

Passive design takes maximum advantages of solarenergy in buildings.

The example of energy conservation are built withthick walls, built in cluster, roof with mud & sun-dried tiles, open water surfaces, vegetation growthetc.


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Basic Concept

The use of this natural sun-energy direct or indirectin the building is the concept of passive design.

Passive solar design can never negate the impactof climate, but it can only minimise.

The word " passive" emphasises on the control ofthe flow of thermal energy by natural means. Itassumes the building as a natural collector.

"Active" system in the other hand is a system

where external energy (Electrical or mechanical) isused to run the system in order to transfer theheat from one place to other.


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Dr.Pahari/ 65-9-3 4

Heating & Cooling in Building

Passive systems provide heating and coolingby using natural energy sources and sinks.

The basic heat gains: Solar radiation

Outside air when warmer than 270C (averageambient temp.)

Internal gains, conventional domestic heatingand lighting


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Heating & Cooling in Building

The main sinks:

The sky and outer space,

Outside air when cooler than 270C(average ambient temperature)

Wet surfaces and vegetation


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Dr.Pahari/ 65-9-3 6

The Heat Gains and Losses

Sun

Air

Temp>270C

Day

Hot surface

Sources of Heat gains

Air

Temp


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Basic Assumptions of Passive Design

The purpose of the natural heating andcooling methods is to provide a comfortableinternal environment.

For this, the external building envelope canbe considered as a membrane that protectsthe indoor space from undesirable climaticinfluences.

It is focused on the energy saving taking into consideration the climatic factors and inharmony with the environment.


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Basic Assumptions of Passive Design

The external envelope will filter-out theworst climatic element in one side and inother side also interacts with out-door

environment to let-in as much radiation aspossible for the natural heating or removeseven internally generated heat for naturalcooling of the building.

The sun and the climate are the centrepoint of passive design and concerns withthe thorough study of the climatic factors.


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Dr.Pahari/ 65-9-3 9

Mode of Passive Heating & Cooling

Direct gain A large expansion of vertical south facing

glass window usually double glazed admitsthe sun's rays, alloying them to strike themasonry floor and /or wall, which acts asthermal storage.

The thermal energy stored in theseelements is distributed to the living spaceby radiation, by convection of room airover the warm surfaces and by conduction.

A correctly designed mass can containinternal temperature swings to 100 C.


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Dr.Pahari/ 65-9-3 10


Direct gain

Solar Radiation

Sunshade to

obstruct solar

radiation during

summer

Curtain to

obstruct during

summer & to

provide access

during winter the

solar radiation

inside buildingHeat conserving

Materials

Glass

window in

south facing

House


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Thermal storage wall This heating mode blocks and collects solar radiation outside

the living space by creating a thermally massive wall betweenit and the sun.

Heat is stored in this thermal mass and distributed to the

living space by re-radiation through the back of the wall,and/or by convection of cool room air passing the warm faceof the mass by natural thermo-siphoning.

This thermo-siphoning effect is created on the sunny face ofthe wall by placing a glazed screen about 50 mm away fromthe wall face, punching holes in the top and bottom of the

wall, and letting room air naturally thermo-siphon and becomewarm. Honeycomb masonry walls are Trombe walls. Horizontally stacked drums of water are Drum wall, Vertical tubes of water are water wall.


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Horizontal drums of waterAbsorbing solar heat

Vertical masonry wallabsorbing solar heat

Vertical Tubes ofwater absorbing solarheat


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Glass window in

front of Trombe

wall

House

SolarRadiation

Sunshade to

obstruct solar

radiation during

summer

Glass window in

front of Trombe

wall

Trombe wall


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Solar green house

This heating mode is the further development of Trombewall, but the space between the glass and the wall hasbeen widened to form a green house.

The greenhouse provides not only a means of heatingbut also a usable living space and the opportunity togrow food and flowers.

Solar green house may be made with; Glazed wall between green house and living space

Massive wall between green house and living space Small green house used as entry porch

Green house cover on the stair


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Glazed wall betweengreenhouse & living space

Massive wall betweengreenhouse & living space

Small greenhouse used asentry porch

Solar green house


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Mode of Passive Heating & CoolingSolar green house

Solar

Radiation

Glass roof in

front of trombe

wall

Trombe

wall

Glazed window

and Glass roof

on South facing

house


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Roof pond

This heating mode transfers thethermal storage to the roof.

It consists of plastic bags of waterthat are supported on a steel deckroof or RCC construction on theroof.

Control is affected by the

positioning of the movableinsulating shutters that are locatedabove the water bags or pond.

Roof pond

Pond

Pondcover


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Roof pondSolar Radiation

Pond or

water drums

condition of

closed covering

condition of

opened covering


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Convective loop In this system an angle solar

collector heats a transportfluid (that can be either air or

water) and, by a thermo-siphoning loop, allows it torise to a thermal storelocated above the collector.

After transferring its heat tothe store, the fluid continuesdown to re-enter the base ofthe collector.

Convective loop

Air space orliquid spaceheating system


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Solar Chart

Solar chart is a graphical representation of the path ofsun in the sky for various days in the year of theparticular latitude.

The hemisphere of the sky is represented by a circularplane diagram, the centre of which represents the

zenith and the outer circumference represents thehorizon line.

The various line of compass are shown alone thecircumference of the chart and the altitude angles arerepresented by concentric circles, the outermostcircumference denoting zero and the centre denoting

900 of altitude. Solar chart can establish the sun's position in the sky

hemisphere.


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Reference angles

i = Incidence angle, a =Altitude Angle, =Azimuth angle

a

i


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Solar Chart..\..\climatic design tools\drawsunpath.exe
http://../climatic%20design%20tools/drawsunpath.exehttp://../climatic%20design%20tools/drawsunpath.exe


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Solar Chart & Its use

Uses of solar charts

The basic use of the solar chart is to findthe position of sun in the sky hemisphere.

This is very important; To determine the intensity of solar radiation,

To design shading device (shape and size) in tothe building,

To define the angle of incidence of solarradiation


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Shading Devices

The devices that are used to block the solar radiationincident on the exposed surfaces of a building,consequently reducing heat gain, are called shadingdevices,

Shadings are normally done in the openings,

The shading devices may be internal or external andthey may be fixed, adjustable or retractable,

The internal devices may be venetian blinds, rollerblinds and curtains,

The external shading devices are much more effective

than the internal arrangement, It is true that more than 90% of heating effect ofsolar radiation is possible to eliminate with efficientuse of the shading devices


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Types of external devices

Vertical devices

Horizontal devices

Horizontal shadow angle

= horizontal shadow angle

= horizontal

shadow angle

= vertical shadowangle

a = solar altitudeangle

tan = tan a * sec

Vertical shadow angle

a


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Types of external devices

Egg-crate devices

Inclined devices

Normallouver

Inclinedlouver

Window

Wall


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Passive techniques in housing

Heat gain prevention techniques Orientation of building

Shading by neighboring buildings

Shading by vegetation/pergolas Shading by overhangs and louvers

Special construction of wall

Solid wall

Mud wall Cavity wall

Textured wall surface


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Orientation of building

Bad Fair Best

N


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Shading by neighboring buildings

BuildingBuilding

Building

Building

Shadow

Shadow

Shadow

Shadow

House enclosed with verandah

Building

Verandah


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Shading by vegetation

Hot air escape

Verandah

Air buffer

Moisture

Slow evaporation

Shady tree

Protection from solar radiation

Room space

Brick wall

RCC slab

Roof shading by Pergolas

Radiation ShadingPartly

RadiationEvaporation


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Shading by overhangs

shade

Roof projection


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Shading by overhangs

House enclosed with verandah

Building

Verandah

Rooms

Ve

r

a

n

dah

Courtyard

Courtyard House


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Special construction of wall

Solid wall

Brick wall

Cavity wall

CavityBrick wall

Cementplaster

Mud wall

Mud wall

Cementplaster


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Design toolsFlow chart of the Energy efficient Building Planning

Building planning

Site planning

1. Energy conservation

3. Active spaceheating/cooling modes

2. Passive spaceheating/cooling modes

1. Energy conservation

3. Active spaceheating/cooling modes

2. Passive spaceheating/cooling modes

Energy efficient

Building Planning


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Design tools

h

8h

Spacing for wind deflection

Vegetable shading

VentilationInsulating earth berming

BERMING for added insulation and wind

Site Planning

Energyconservation

Passive spaceheating/cooling

Bad Fair Best

N

250250S

* 150 for due south obstruction* 100 for any other obstructions

N-Maximize in south-Minimize in north, east, west

Layout

Shape

OrientationSpacing


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Design tools

Building Planning

Energyconservation

Passive space

heating/cooling

InsulationVentilationTemporary zoningWindowsLightingBuilding volume

ColorDomestic hot water

GeneralDirect gainThermal storage wallSolar green houseRoof pondConvective loop


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Thank you

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Application of Passive Solar System

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